[openssl/openssl] 5cd179: Deprecate SPT threading support on NonStop.

[Randall S. Becker]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 5cd17920167a8b4f7a81722a1ed3b514115702de
      https://github.com/openssl/openssl/commit/5cd17920167a8b4f7a81722a1ed3b514115702de
  Author: Randall S. Becker <randall.becker at nexbridge.ca>
  Date:   2023-12-12 (Tue, 12 Dec 2023)

  Changed paths:
    M Configurations/50-nonstop.conf
    M NOTES-NONSTOP.md
    M crypto/bio/bio_sock.c

  Log Message:
  -----------
  Deprecate SPT threading support on NonStop.

This fix removes explicit support for the SPT threading model in configurations.
This also reverts commit f63e1b48ac893dd6110452e70ed08f191547cd89 that were
required for SPT but broke other models.

Fixes: #22798

Signed-off-by: Randall S. Becker <randall.becker at nexbridge.ca>

Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Neil Horman <nhorman at openssl.org>
Reviewed-by: Hugo Landau <hlandau at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22807)